A transmission mechanism mounted on a rack and driven by a foot pedal to move a movable center rod and a superior cymbal at said movable center rod relative to a fixed inferior cymbal, the transmission mechanism including an oscillating member, which has a horizontal block connected to the foot pedal by a chain and a vertical block, a first universal joint connected between the vertical block of the oscillating member and the movable center rod, a second universal joint securely mounted on the rack at a bottom side, and a coupling bolt turned about a pivot pin at the vertical block of the oscillating member and securely connected to the second universal joint.